Electric-arc-welding system.



J. KJEKSTAD.

ELECTRIC ARC WELDING SYSTEM.

'APPLICATION FILED OCT. 19, 1918.

gay: Z

r0 GROUND z I 2d 3 j II /J 0 z Z Z.

WITNESS: INVENTOR.

A TTORNEYS.

JOHANNES KJ'EKSTAD, OF BROOKLYN, NEW YORK.

ELEGTRIC-ARC-WELDING SYSTEM.

Specification of Letters Patent.

Patented Jan. 21, 1919.

Application filed October 19, 1918. Serial No. 258,901.

To all whom it may concern.

Be it known that I, JOHAXNES KJEKs'rAn, a subject of the King of Norway,residing at the city of Xew York. borough of Brooklyn. and State of NewYork, have invented certain new and useful Improvements inElectric-Arcelding Systems, of which the following is a full, clear, andexact description.

My invention is broadly applicable to both metallic arc welding andcarbon arc welding, and has for an object the provision of means in sucha system for automatically keeping the energy at the are constant withincertain limits.

Another object is to obtain this result with a minimum dissipation ofenergy in external resistances or other regulating devices, wherebyeconomy in energy consumption is effected.

Another object is to provide a regulating system capable of use with oneor a plurality of welders in the same system.

Other objects and advantages of my invention will appear from thefollowing description.

Various systems have heretofore been proposed for stabilizing wattageconsumption at the arc, but these have commonly comprised automaticallyvariable resistances, which. of themselves. consume considerable of theenergy supplied to the circuit. My invention comprehends as a regulatingdevice an auxiliary source of energy operative to supply to the circuitmore or less energy as is demanded to maintain the wattage substantiallyconstant. In its preferred adaptation, my invention contemplates anautomatic regulating device, which is responsive to the variationsin'current to inversely regulate the voltage impressed upon the line.and thereby maintain the wattage substantially constant.

More specifically, the regulating device is itself a source ofelectro-motive force, which is positive or active relative to that ofthe main generator. so long as the current is below a predeterminedamperage, and is negative or counter when the current rises above thepredetermined amperage, while at the predetermined amperage theregulating device is inactive or passive.

In this specific embodiment. the voltage may at all times be consideredto be resultant of two components. In the equation z-a w, in which 2'equals the voltage, and a as r or the electro-motive force of the maingenerator, and v, is a variable counter electro-motive force. e thenhave the equation In this equation o, and a are directly variable, withthe result that w remains substantially constant.

Figure l is a diagram of one embodiment of my invention showing a mainand auxiliary generator with their circuit arrangements.

Fig. 2 is a diagram showing the circuit arrangement of a systemembodying my invention and comprising a plurality of welding arcs.

In my improved system, I use a main (1. c. generator of such size as togive the desired voltage and amperage for one welder, if only one is tobe used in the circuit, or of such size as to give the same amperage foreach welder if a plurality of welders are included in the circuit. Inseries with the main generator is used an auxiliary regulating generatorfor each welder, which is differentially wound with the shunt coilexcited by the main generator and a series coil so proportioned andconnected as to neutralize the shunt field when a predetermined amperageis passing through the arc.

Referring to Fig. 1, the main generator 1 is shunt wound and of suchsize and capacity as to generate sufficient electro-motive force toforce the desired current across each are under proper conditions. \Vewill assume, for example. that the generator 1 generates '20 voltspressure with a current of 150 amperes across each arc. under ideal areconditions. This voltage remains substantially constant while theamperage and hence the wattage varies with the resistances across thearc.

To compensate for this variation, the auxiliary regulating generator 2is used in series with the main generator. The positive tive brush ofthe armature 2 is connected to the series field coils 2 which areconnected to the wire 4: leading to the ground,

and the negative brush of the main generator is connected by a wire 5 tothe electrode.

- The shunt field 2 of the auxiliary generator is connected across theleads from themain generator armature, and the two field windings 2 and2 are wound in opposition to each other, the series coils being soproportioned as to neutralize the shunt field when the predetermineddesired amperage is passing through the arc, which in the supposed caseis 150 amperes.

The shunt coils 2 of the auxiliary generator 2 serve as a separatesource of excitation for the field, which is substantially constant. Ifwe assume that the auxiliary armature on open circuit, by reason of theshunt field excitation, gives 40 volts in the same direction as the maingenerator, with which it is in series, then the total electro-motiveforce to start the arc will be 60 volts. When 150 amperes pass throughthe arc and the series coils 2 of the auxiliary armature, the shuntfield 2 of the auxiliary .armature is neutral-.

ized, and the armature 2 then gives no voltage and acts only as areactance. The are will then have the twenty volts of the maingenerator, and if the current in the arc falls 3 below 150 amperes, theauxiliary generator will supply some voltage proportionate to the extentof drop of the amperage, which will help to maintain the arc; and if thecurrent in the arc goes above 150 amperes, the auxiliary armature willgenerate a-volt- .age against the main generator, and tend to prevent anexcessive rise in current. In other words, the auxiliary generator actsas a .booster when the current across the arc is below a predeterminedamperage, and acts stand that the size and capacity of the to buck themain generator, if the current rises above the predetermined amperage.

Bythis means I am enabled to have at all times substantially a constantamount of energy in the arc, .while dispensing with all seriesresistances for steadying the arc.

It will be understood that the figures given above are only by way ofillustration, and those skilled in the art will readily undereneratorsmay be varied to obtain any desired result. 'They may-be soproportioned, for example, as to have the same size frame, in which caseall arts, except field coils, will be interchangea Is, an obviousadvantage in appearance and manufacture.

Fig. 2 illustrates one way in which my invention may be applied to asystem including a plurality of arcs. In the system shown there arethree arcs although it will be unbeing only necessary to make the maingenerator 1 of the requisite capacity. For instance, if 150 amperes at20 volts pressure be desired at each arc, then in the system shown thegenerator 1 will have a capacity of 20 volts and 150 amperes. Anauxiliary generator similar to the one above described is used for eachwelder.

It is obvious that various modifications may be made in the constructionshown in the drawings and above particularly described withln theprinciple and scope of my invention.

I claim;

1. In an electric arc welding system, the combination with means forimpressing a voltage upon the welding circuit, of a regulating deviceoperative to impress another and a variable voltage upon the circuit.

2. In an electric arc {welding system, the

combination with means for impressing a. voltage upon the weldingcircuit, of a regulating device responsive to the current in the weldingcircuit to impress another and a variable voltage upon the circuit.

3. In an electric arc welding system, the combination with a maingenerator in the welding circuit, of an auxiliary regulating generatoroperative to impress a variable voltage upon the circuit and maintainthe wattage at the are substantially constant.

4. In an electric arc welding system, the combination with a constantvoltage generator in the welding circuit, of an auxiliary regulatinggenerator operative to impress a voltage upon the circuit and responsiveto the current in the circuit to vary its voltage.

5. In an electric arc welding system, the

combination with a source of electro-motive force, of a regulatingdevice responsive to variations in the welding current for impressingupon the circuit a variable counter electro-motive force.

6. In an electric arc welding system, the combination with a constantvoltage generator in the (welding circuit, of an auxiliary regulatinggenerator operative on open circuit to impress an additionalpredetermined voltage upon the line and upon closed circuit to generatea counter electromotive force variable with the current in the circuit.

7 In an electric arc welding system, the combination with a source ofelectro-motive force in the welding circuit, of an auxiliary regulatinggenerator in the circuit separately excited or generating anelectro-motive force and responsive to the variable current in thecircuit to generate a counter electro-' motive force and thereby varyits voltage impressed upon the line and maintain the wattage at the aresubstantially constant.

8. In an electric arc welding system, the combination with a source ofelectro-motive force in the .welding circuit. of an auxiliary ratelyexcited for generating an electro-n'io 9. In an electric arc weldingsystem, the

combination with a source of electro-motive force in the weldingcircuit, of an auxiliary regulating generator in the circuit having twocomponents to its field excitation, one a, separate excitation and theother a series excitation, .the windings of the components being opposedand proportioned to neutralize each other at a predetermined current inthe series winding.

10. In an electric arc welding system, the

combination ,with a main constant voltage generator in the weldingcircuit, of an auxiliary regulating generator in the circuit having itsarmature connected in series with the main generator'and having itsfield energized by a series winding and by a winding in shunt with themam generator, theseries and shunt windings being opposedandproportioned to neutral ze ata predetermined current in the seriesWinding.

In w tness ture.

, JoHANNEs KJEKSTAI).

whereof I subscribe my sigma-1

